The German teen drama Allein gegen die Zeit is aimed at teens and young adults. Yet, it can easily be compared to high-profile thrillers like 24. It's first season featured a school hostage taking, a fascist political conspiracy, attempted mass murder, an unvilified portrayal of ethnic gang members, police corruption, depression, gun violence and liberal swearing. The second season was even Darker and Edgier, throwing cruel and unusual deaths, terrorism, and lethal biological weapons into the mix. Especially jarring since KiKa is aimed at children younger than thirteen.
On seeing the script of Episode One of Children of the Stones, director Peter Graham Scott remarked, "And this is for children?"
Doctor Who itself is considered family viewing, despite its dark tone of certain episodes and surprising amount of sexual innuendo and it is shown around the supper hour on a Saturday. Doctor Who is nearly fifty years old and neatly matches the second paragraph of this trope's description. It's very much seen as a family/children's show, but it's been violent from the very beginning. A BBC audience research survey conducted in 1972 found that Doctor Who was the most violent show it produced at the time (cf. http://en.wikipedia.org/wiki/Doctor_who). The show was especially violent during the first few Fourth Doctor seasons, consistently getting complaints, and the show was also so violent in 1985 that it got the show cancelled for 18 months. For instance, The Brain Of Morbius (1976) featured a man getting shot in the stomach with an explosion of blood, then crawling, dying, down a corridor.
Even the first few stories could be really dark. In the first story "An Unearthly Child" the Doctor is a quite morally ambiguous figure, and there were some surprisingly violent scenes, such as a Caveman with his chest ripped open and a cave of broken skulls. "The Edge of Destruction" uses haunted house tropes and has Susan wildly stabbing a bed with scissors.
Season 22 is notorious for this, showing someone having their hands crushed and showing several people being stabbed to death. This is lampshaded in "Vengeance on Varos".
Current show runner Steven Moffatt has written about how annoyed and insulted he is whenever people use the phrase "kid's show" as a derogatory thing.
The Haunting Hour often has gruesome deaths, frequent moments of Getting Crap Past the Radar, and episodes that rely more on real-life scares along with the usual use of ghosts, ghouls, vampires, and freaky creatures. Then there are episodes like "Head Shot," "Sick," "The Cast," "The Weeping Woman," "Checking Out," "Red Eye," and "Terrible Love" that show that sometimes the scariest things we experience are real and the monsters we encounter are people with warped personalities (which "Head Shot," "Red Eye," and "Terrible Love" showed with all the subtlety of a bitch slap upside the head).
Ik Mik Loreland, the educational programme that traumatized an entire generation of Dutch children. It was specifically targeted towards six-year-olds to teach them to read and write. The plot involves Loria, a land where everyone loves reading and writing, and the one-eyed monster Karbonkel who can't do these things and gets so madthat he magics away everyone's ability to read and write, scattering the words all over the world. A girl named Mik takes it upon her to get them back and Karbonkel pursues her and attempts to stop her. Karbonkel was a frightening antagonist who regularly showed up in childrens' nightmares, while many of the locations Mik visited on her journey were creepy and bizarre. Every year when it was rerun, debates would erupt among parents and school teachers about the appropriateness of the show. According to Word of God, Twin Peaks was a major influence.
The Ink Thief had a very gothic style to it, even though it was mostly kid-oriented. Richard O'Brien's character was pure terror, though.
Knight Rider is often stereotyped as a kids' show because it has one hero and his super cool super car, but the first season itself is loaded with episodes about politics, corrupt police, framed murder charges, a lover implicated in soliciting crime and the murder of a sleaze magazine owner- plenty of murders in the first season. The pilot is surely not for kids. Plenty of gunshots fired in the show actually hit- and a few kill. Contrast that with The A-Team which has only two casualties in the whole run and almost none of the shots hit.
Maddigan's Quest is quite possibly the only children's show to have featured mind-altering drugs and cannibalism in the same episode. The series also contains child labour, implied sexual slavery (with slavers refusing to sell a baby to the Big Bad to be killed because she'd fetch a higher price as wife material), repeated attempts at infanticide, and Body Horror.
Time Force is especially the one with the most grown-up subject matter. In the future, Designer Babies are the norm, and the resulting mutants are outcasts and became criminals just to survive. The Starscream turns out to be The Starscream because Ransik betrayed him first in his previous identity because he couldn't see past his hatred of humans even when one had just helped him. You get a story about man's inhumanity to man, villains we created and mistreated but who went from La Résistance, and off the slope into The Revolution Will Not Be Civilized, and the Cycle of Revenge. Yes, this is the same show that once had as a villain's plot, "destroy the Pink Ranger's parade float just to make her feel bad!" nine or so years previously.
Press Gang was aimed at children and teenagers, was frequently hilarious...and featured topics such as glue-sniffing leading to accidental death, child sexual abuse, a gun seige at a newspaper office, a gas leak resulting in a building blowing up (half of the episode was about one survivor, trapped in the rubble, trying to keep another alive until the rescuers could get to her...which didn't work), teachers having extramarital affairs, and so on. Storylines also focused on a suicide, a reporter coaxing a confession of manslaughter out of a half-blinded gang member over the phone, and a death by drug overdose (Lynda was not overly sympathetic). There's a reason that its co-creator and sole scriptwriter went on to become Executive Producer of Doctor Who...
While more clear-cut kid-friendly than the family show Doctor Who, some episodes of The Sarah Jane Adventures — *cough* "Day of the Clown" *cough* — are not the kind of thing you'd want to let children watch alone...
Aired in syndication and not heavily promoted, Superhuman Samurai Syber-Squad got to fly under the radar. Though "destroying" the heroes came up as a villainous goal a lot just 'cause it's how bad guys talk, Never Say "Die" wasn't in effect, and some of the things the Monster of the Weekdid to people could get kind of dark. All water faucets suddenly spew hydrochloric acid! Your wristwatch takes control of your hand and you nearly choke yourself to death while the monster laughs about how you're going to die! Kilokhan also once pulled a Venjix, taking over nukes and nearly causing World War Three. Oh, what about the Christmas episode where Kilokhan finds out who Servo is, transfers himself to Sam's computer, and outright kills him with an electric blast? Malcolm, Kilokhan's sidekick until Kilo tried to pull a You Have Outlived Your Usefulness on him, was told to Take Up My Sword, but when he tried to transform, only the Servo wrist device was pulled into the digital world, and Servo - Sam within as always - activates. Sam defeats Kilokhan with a Dangerous Forbidden Technique, but doesn't know if he'll ever be able to return to his human form, and departs into the information superhighway for parts unknown. Apparently, unexpected renewal is what kept this from being how the series ended. (More episodes are made, but the second full season that was talked about doesn't come, so it actually gets No Ending, the last episode being one just like any other.)
The Hamas-made kids show Tomorrow's Pioneers. It has death, murder, violence, promotion of hatred, and things that Westerners wouldn't really consider fit to be in a kids show.
Super Sentai is especially surprising to some American audiences because of differences between Japan and the US. In Super Sentai, they make frequent use of blood, have characters actually die, and actually show guns. In the US, none of this could be shown on a kids show, so when Super Sentai is adapted into Power Rangers, these are used very rarely, if at all. On the other hand, in Japan it's a common viewpoint among those who have seen both Super Sentai and Power Rangers that Power Rangers is actually more mature, because the lack of wacky humor is more noticable than the toning down of violence.
Even when taking cultural standards into consideration, the Kamen Rider franchise's run from 2000 to approximately 2004-2005 is largely characterized by its ability to introduce mature tropes into the series. Kamen Rider Kuuga, for example, is one of the few Tokus that has gotten away with depicting the murder of minors. The peak of this renaissance can generally be agreed to exist between Kamen Rider Ryuki and Kamen Rider 555 which both subvert the traditional Rider Vs Monster scenario in their own ways. Word of Godsays that after four years of Kamen Rider Double's formula, Kamen Rider Gaim is intending to steer the creative direction of the franchise back to that period... via "Urobutchery."